Project 3: Rapid Non-invasive Radiation Biodosimetry through Metabolomics. Metabolomics has been established as a non-invasive approach to basic radiation biodosimetry, and has the potential to discriminate specific features of radiation exposure that are relevant to triage. The proposed studies will characterize the metabolomic effects of dose rate (from 0.25 Gy per day to 2 Gy per second), exposure to the internal emitter 137Cs, and the neutron component of improvised nuclear device (IND) radiation to develop radiation biodosimetry more relevant to real-world exposure scenarios. Dose estimates provide only an indication of the average radiation injury expected across a population. It will also be important to develop predictors of individual radiation injury response and outcome. Early metabolomic predictors of mortality due to late lung injury, as well as signatures of lung injury and recovery, will be developed. Related studies will develop early predictors of mitigator effectiveness, since early indication of treatment failure will give the opportunity to try alternate therapy on an individualized basis. Radiation exposure is known to trigger many inflammation-like processes, suggesting that chronic inflammatory or immunosuppressive conditions, which exist within the human population, may have the potential to confound radiation biodosimetric signatures in affected individuals. To begin addressing this possibility, investigation of the impact of inflammatory pathways on radiation metabolomic biomarkers will be undertaken using mouse models. All the research proposed in Project 3 is ultimately directed toward practical implementation for biodosimetry. Mass spectrometry (MS) is now routinely used in major clinical laboratories, but efficient sample collection, processing, and transport will be required to interface with the available clinical instruments. In support of this larger goal, an integrated blood sample collection and processing card system will be developed in collaboration with the Sample Engineering Core to obtain and pre-process blood samples for shipping to an MS facility. The metabolomic studies proposed in this project will be complemented by investigations of cytogenetic endpoints (Project 1) and transcriptomic profiling (Project 2) and will benefit from shared biological samples and experimental designs. The program Cores will further enhance the planned research by centralizing and standardizing routine functions, such as mouse handling and irradiations, and by providing unique resources, such as the IND-spectrum neutron source and the variable dose rate external 137Cs irradiator (Irradiation Core), and the hematopoietically humanized mouse for biodosimetry (Mouse Core).